In the field of fire protection, most valves are based on two basic valve principles: the clapper design and the diaphragm design. A base valve may be utilized for different functions and/or systems, such as deluge, wet system, dry/pre-action valves, pressure reducing, deluge reducing and deluge on/off applications. The base valve is configured to fulfill those varied functions by external connections and components, collectively known as ‘trim’. Historically, the clapper valve has been most common, however, in recent years, with the introduction of special fire protection applications, the trend is more towards use of the diaphragm design. The base valve has at least a valve body, an inlet in fluid communication with an inlet chamber which can hold a fluid supply, and an outlet chamber which can receive fluid from the inlet chamber and pass the fluid to an outlet. The fluid in the input will be referred to herein as a ‘primary’ fluid. A valve may be in a “closed”, or “standby” state where the valve impedes flow of fluid between the inlet and outlet, and an “opened”, or “activated” state in which fluid communication is established between the input and output chambers, and fluid is allowed to flow between the input and the output. In a clapper valve the input chamber is cupped by a clapper that is mechanically held closed during the standby state and the clapper is released in the open state. The clapper valve will stay in the open state, until it is manually reset, therefore it cannot be operated as an on/off valve which requires an automatic reset.
Diaphragm valves have a diaphragm chamber in addition to the input and output chambers. When the diaphragm chamber is pressurized, the pressure in the diaphragm chamber causes the diaphragm to move to a closed state in which a sealing portion of the diaphragm impedes primary fluid flow between the inlet to the outlet, and thus the valve is in a closed state. When the pressure from the diaphragm chamber is released, the valve transfers to the open state, and primary fluid is allowed to flow from the input to the output. One example of a diaphragm valve is described in U.S. Pat. No. 8,616,234, titled “FLUID CONTROL VALVE SYSTEM AND METHODS” filed on Dec. 3, 2008, however many other examples and embodiments are known.
A dry/pre-action system is a type of fire protection system that is commonly used, especially where a sprinkler system or a portion thereof may be exposed to sub-freezing temperatures. In such systems, a primary fluid source is separated by a valve from a piping and sprinklers arrangement known as the ‘dry’ side. The dry side is kept pressurized at positive pressure by a compressed secondary fluid, which in many applications comprises air. When a sprinkler or other fire sensor is activated, the positive pressure of the secondary fluid drops, causing the valve to ‘trip’, i.e. to transfer from a standby to an open state, and send primary fluid from the source to the dry side of the system.
Certain fire protection systems utilize the main valve controlling the fluid flow into the fire protection system as an activator of an alarm. When the valve is opened fluid is used directly or indirectly to activate an alarm, which in most cases is electric. A valve utilized to activate an alarm will be referred to as an ‘alarm valve’.
Many fire protection standards for both wet and dry systems require an intermediate chamber between the inlet and the outlet, the intermediate chamber being connected to an alarm port. If primary fluid leaks behind the seal provided by the valve, such leak will be detected by leakage of primary fluid from the alarm port, and an alarm will be activated. In most existing valves rigged for dry/pre-action operation, an additional check valve is disposed between the primary valve and rest of the dry side, the check valve acting to define the intermediate chamber between the check valve and primary valve. Patent application WO 2008/051871 to Ringer discloses an intermediate chamber which is integral to the valve body. Other valves, such as disclosed by US patent publication number 20090272549 to Feenstra et al., incorporate a check valve within the valve body. However any fire protection system where activation is based on dropping pressure of secondary fluid in the dry side suffer from a common problem: a leakage in the dry side may cause a system failure, as the detection of fire may fail to activate the valve.
There is therefore a long felt, yet heretofore unanswered need for a compact valve with efficient sealing capability, be configurable in several ways, which may provide an alarm for leakage of fluid from piping in at least one side, and optionally from both sides of the valve, and further optionally to differentiate between leakage from the different sides.